Temporary IE

Drawing of the scheme how the two peltiers, heat sink and fans could be connected

Heating and cooling unit 13/6/2012
OK we are going to play with the relay circuit switching on and off one or two peltier modules (100 w) and fans (120 - 80 mm "PSU") by arduino. I wonder if 250 W power source from PC power supply unit would be suitable? We can get it for free ... We want to use at least one 120 mm axial-flow fan type for taking out the heat/cold from the heat sink connected to the peltier. Where can I find more about the static pressure values etc.

A fan with high static pressure is more effective at forcing air through restricted spaces, such as the gaps between a radiator or heatsink; static pressure is more important than airflow in CFM when choosing a fan for use with a heatsink. The relative importance of static pressure depends on the degree to which the airflow is restricted by geometry; static pressure becomes more important as the spacing between heatsink fins decreases. Static pressure is usually stated in either mm Hg or mm H2O.

because in our case we have a heat sink with fins just behind the ventilator. The idea in this moment is to connect two peltiers to one heat sink, one peltier on each side. When we need to cool, one with the "cold side" attached to the heat sink is switch on + the fan in the internal duct and the external fan cooling the external heatsink by the hot side of the peltier are switched on too. When we need to heat up the second peltier with the hot side connected to the heat sink wee switch it on so is the internal fan and if necessary external fan cooling the passive heat sink on the external cold side of the peltier. In this case there would be just one heat sink in the internal circulation connected on one side to the hot side of the peltier module and on the other side to the cold side of peltier module. This would decrease the frictions of air with another heat sink. If the changing of the polarity of the peltier device is easy to do and it doesn't decrease the life span of the module too much, we could do that too.

So to play with the set up one internal heat sink, two peltiers and arduino we need: